Farr, best known for her role as Megan Reeves on the CBS crime drama “Numb8rs,” will play a private investigator who fears that her illness may prevent her from solving the most important case of her career. Farr will appear in episode 604 of the show, which centers on a concierge doctor in the Hamptons.

Farr previously starred in “Rescue Me” and “Like Family,” in addition to guest starring on “Modern Family,” “Californication,” “Private Practice,” “The Secret Life of an American Teenager” and another USA drama, “White Collar.”

“Royal Pains” is written and exec produced by Andrew Lenchewski and Michael Rauch.